start_domains.js

var express = require('express'),
    app     = express(),
    server  = require('http').createServer(app),
    io      = require('socket.io').listen(server)
;

io.set('log level', 1);
io.set('transports', ['websocket', 'flashsocket', 'htmlfile', 'xhr-polling', 'jsonp-polling']);

global.io = io;

app
.use(express.vhost('domain1.com', require('/home/user/project1').app))
.use(express.vhost('domain2.com', require('/home/user/project2').app));

server.listen(80);